Platinum (Pt) has been intensively studied as an effective cocatalyst for photocatalysis, but most reports have focused on metallic Pt rather than PtO. Here, Pt/PtO nanodots were deposited on porous yolk-shell La₂O₃ microspheres. XRD patterns and XPS analysis demonstrated the coexistence of Pt and PtO, which was beneficial for photocatalytic performance. SEM images showed the yolk-shell structure of La₂O₃, and TEM images demonstrated that the Pt/PtO nanodots were uniformly distributed on the La₂O₃ microspheres. The rate constant of the hybrid was calculated to be 0.00656 min-1 for methyl orange (MO) degradation, while that of bare La₂O₃ was only 0.00303 min-1. This work suggests that the use of the deposited cocatalyst Pt/PtO on La₂O₃ microspheres is a promising strategy for the degradation of organic pollutants.